The equivalent of 24 gallons of frozen water, mixed in with the Stilton, Cheddar and Brie that was thrown into the air when a rocket was deliberately crashed into a crater near the Moons south pole last month. It is far from the science fiction fantasy of an underground lake, but still pretty impressive for a satellite long dismissed as cheesy.
http://www.telegraph.co.uk/science/science-news/6564450/Water-found-on-Moon-by-Nasa-QandA.html
http://www.rathergood.com/moon_song